The present invention relates to a method of and an arrangement for winding helixes of elastic synthetic plastic and metal wire. More particularly, the invention relates to a method of and arrangement for winding and forming helixes with windings including substantially straight winding legs and head curves connecting the winding legs to one another, for example for flat shaped articles, such as sieve bands or composite bands for paper machines and the like.
Flat shaped articles of the above-mentioned general type are disclosed, for example, in the DE-PS No. 2,419,751 and DE-OS No. 2,938,222. In accordance with the DE-PS 2,419,751 the wire helixes have a pulling spring-like tensioning which produces contractions of the neighboring wire helixes of the flat shaped article against one another. In the DE-OS No. 2,938,222 the helixes do not have pulling-spring like tensioning. Their wire is torsion-free, so that the service life of the thus formed flat shaped article is increased. Both types of the flat shaped articles possess, however, some disadvantages.
Flat shaped articles which have helixes with mainly round or slightly oval wires with constant cross-section naturally have a high air permeability. It is required here that the intermediate space between the carrying winding legs correspond to the wire diameter. For reducing the high air permeability, for example during the paper manufacture, filling elements are introduced into the helixes. Though they influence in the air permeability, they require a considerable labor expenditure. The filling elements are composed mainly of cotton or synthetic plastic parts which can be introduced into the helixes with relatively great difficulties. In addition to the increased labor consumption, the price of the thus produced material increases as well. Helixes of round wire possess also the property that the paper during its manufacture is in a point contact with the flat shaped article. This leads to printing of the winding legs on the finished paper. The point-like or edge-like contact between the carrying winding legs of the helixes of the flat shaped articles and the paper leads to the fact that the heat flow between the calendar roller and the paper is weak because of the only small abutment possibilities and therefore small contact surfaces. In order to eliminate this disadvantage the helixes are produced of flat wires. The carrying winding legs of the flat wires provide for greater contact surfaces with the paper. However, as before an increased air permeability of the flat shaped article must be taken into consideration, since the distance between the individual windings of the helixes are great. This can lead to the phenomenon that the paper during its manufacture has an inclination to flatter. Moreover, there are difficulties during manufacture of the flat shaped articles when the helixes of flat wire are used.
In order to combine the advantage of easy manufacture of a flat shaped article with round wire helixes with the advantage of wider supporting surface and better heat transfer with a limited air permeability, it has been proposed to form the carrying winding legs so that they have flat supporting surfaces with a width which is greater than the wire diameter or the wire width of the head curves. It has been shown that these helixes are assembled as easy as the helixes of a round wire, or since the used helixes are more accurate and smooth than the known helixes. The intermediate spaces between the individual winding legs can be greater or smaller as needed. Here not only advantageously wider flat receiving surfaces of the carrying winding legs are obtained, but also an air stream of desired power is provided without insertion of filling elements between the winding legs or inside the helixes. These flat-shaped articles are disclosed in U.S. patent application Ser. No. 513,986.